Bearing construction for railway car axle journals



T. J. SWEGER Jan. 2, 1968 BEARING CONSTRUCTION FOR RAILWAY CAR AXLE JOURNALS Filed March 12, 1965 Eu M V 1 Ill United States Patent 3,361,492 BEARING CONSTRUCTION FOR RAILWAY CAR AXLE JOURNALS Theodore J. Sweger, Naperville, Ill., assignor to Illinois Railway Equipment Company, Chicago, Ill., a corporation of Illinois Filed Mar. 12, 1965, Ser. No. 439,171 3 Claims. (Cl. 308-40) ABSTRACT OF THE DISCLOSURE To provide complementary load transmitting surfaces on journal bearing stops used to limit relative horizontal movement of the journal bearing in a railway car journal box, a film of bearing material is applied to the journal bearing contacting side of each stop which film is capable on initial contact by the axle journal of forming such a surface to avoid squeezing out of a film of lubricant on the axle journal.

This invention constitutes an improvement over the railway car journal box construction shown in US. Patent No. 3,115,374, issued Dec. 24, 1963, in the name of M. S. Johnson. It relates to the construction of journal bearing guides or stops in railway car journal boxes.

Journal stops are mounted on the inner sides of the vertical side walls of railway car journal boxes normally out of engagement with the axle journal therein for limiting the relative movement therebetween during acceleration, deceleration and application of braking forces. Since it is not practical to position the axle journal in the journal box with a high degree of accuracy, the surfaces of the bearing metal of the journal stops juxtaposed to the cylindrical surface of the axle journal are vertical planar surfaces. When the initial application of force causes the cylindrical axle journal to engage one or the other of these vertical planar surfaces, the area of contact is relatively small. Theoretically it is a straight line. Because of the extremely high unit pressure, a film of lubricant on the axle journal is squeezed out and metal to metal contact occurs. This is undesirable since relatively high heat is generated due to friction and rapid wearing away of the contacting surfaces takes place. It is only after the bearing construction has been in operation for a relatively long period that the surface of the journal stop is worn to a cylindrical shape conforming to the cylindrical surface of the axle journal. When this takes place, there is a relatively large area of contact between each journal stop and the axle journal on engagement thereof with the result that the film of lubricant can be maintained therebetween. Thereupon, further wearing away of the juxtaposed surfaces is materially reduced.

Among the objects of this invention are: To provide for making available a relatively large contact area between a journal stop and the juxtaposed axle journal in a railway car journal box immediately upon the initial contact engagement therebetween; to cover the vertical contact surface of the journal stop formed of wear resisting bearing metal with a layer of material having lesser wear resisting qualities which layer is capable of being deformed on contact by the axle journal to provide a complementary cylindrical load transmitting surface having a relatively large area of contact engagement such that a layer of lubricant can be maintained therebetween; to employ for the layer of material relatively soft bearing metal, such as lead indium alloy, fiuorocarbons, such as polytetrafluoroethylene, elastomeric compounds and the like; and to apply the layer of material to the journal stop bearing metal by bonding, heat and pressure, adhesive, electro-plating, or molten metal spray, depending upon the material.

3,361,492 Patented Jan. 2, 1968 In the drawing:

FIG. 1 is a vertical sectional view showing a cross section of a railway car journal box with the axle therein, this view corresponding to FIG. 1 of the patent above referred to.

FIG. 2 is a sectional view, at a greatly enlarged scale, showing the initial contact engagement between the cylindrical surface of the axle journal and one of the vertical planar surfaces on one of the journal stops.

FIG. 3 is a view, similar to FIG. 2, and shows how the juxtaposed surfaces of the axle journal and the journal stop are complementary after a relatively long period of usage.

FIG. 4 is a view, similar to FIG. 2, and shows how the journal stop is modified in accordance With this invention to have a layer of deformable material to receive the initial contact of the journal bearing and provide a relatively large contact area therewith.

FIG. 5 is a view, similar to FIG. 4, and shows how a complementary cylindrical surface is immediately formed on the journal stop following initial contact therebetween so as to provide immediately the desired large contact area between the axle journal and the journal stops, one or the other, while still retaining rigidity of the journal stops to limit the horizontal movement of the axle journal relative to the journal box.

In FIG. 1 the reference character it designates, generally, a railway car axle having an axle journal 11 provided with a cylindrical bearing surface 12 having an axis of rotation as indicated at 13. The railway car axle 10 projects into a railway car journal box, indicated generally at 14, which has a fiat top 15, a curved bottom 16, containing a lubricant 17, such as oil, and vertical side walls 18 and 19. The journal box 14 may form an integral part of a railway car side frame. Overlying the axle journal 11 is a journal bearing 20 having a babbit metal liner 21 initially formed with a cylindrical surface complementary to the cylindrical surface 12 of the axle journal 11. A wedge 22 is interposed between the flat top 15 of the journal box 14 and the upper side of the journal bearing 29.

A double headed arrow 23 below the axle journal 11 indicates that the latter moves horizontally relative to the journal box 14 in one direction or the other depending upon whether the car is accelerating, decelerating, or the brakes are being applied. It is to limit this relative horizontal movement that journal guides or stops 24 and 25 are provided on diametrically opposite sides of th axle journal 11. The journal stops 24 and 25, formed of wear resisting bearing metal such as bronze, are carried by the journal stop mounting means, indicated generally at 26 and 27, which are mounted on the inner sides of the vertical side walls 18 and 19. The construction thus far described with reference to FIG. 1 is that which is shown in the patent above referred to.

As a practical matter it is not possible to position the axle journal 11 in the journal box 14 with the axis of rotation 13 located with a high degree of accuracy in a Vertical plane. The inaccuracy may result form variation in the tolerances of the diameter of the cylindrical surface 12, variations in thickness of the babbit metal liner 21, etc. The double headed vertical arrow 28 near the lower part of FIG. 1 indicates that the axis of rotation 13 of the axle journal 11 may vary somewhat.

It is because of this variation in the location of the axis of rotation 13 that the journal stops 24 and 25 are provided with vertical planar surfaces 30 and 31 which normally are spaced as indicated at 32 and 33 from the cylindrical surface 12. It will be appreciated that the surfaces 30 and 31 are not initially formed having a center of curvature along the axis of rotation 13 of the axle journal 11 since the position of it is variable while e) the positions of the journal stops 24 and 25 are fixed on the vertical side walls 18 and 19.

FIG. 2 shows what takes place on the initial contact by the cylindrical surface 12 with the vertical planar surface 30, for example, of the journal stop 24 on rotation of the axle journal 11 in the direction indicated by arrow 36. Since the surface 12 of the axle journal 11 is cylindrical and the surface 30 of the journal stop 24 is planar, the contact engagement therebetween is a straight line and thus a small contact area 37 is available therebetween. Because of the small contact area, the unit contact pressure is correspondingly high.

As the axle journal 11 rotates, it picks up lubricant 17 from the lower portion of the journal box 14 and carries it in the form of a film, indicated at 38 in FIG. 2, over the surface 12 and underneath the babbit metal liner 21. Because of the relatively high unit pressure due to the small contact area 37 between the cylindrical surface 12 and the planar surface 30, the film 38 of lubricant is squeezed out of this contact area or is prevented from entering it. As a result, metal to metal contact takes place between the axle journal 11 and the journal stop 24. The resulting friction generates heat and produces excessive wear on the journal stop 24 since it is the softer of the two contacting metals.

Ultimately, as shown in FIG. 3, the wearing process continues until a cylindrical contact surface 39 is worn in the journal stop 24 that is complementary to the cylidrical surface 12 of the axle journal 11. This is accompanied by enlargement of the contact area therebetween and a consequent reduction in the unit pressure such that the film 38 of lubricant can be maintained between the axle journal 11 and the journal stop 24. Thereafter, substantially no further wear occurs, as long as the axis of rotation 12 of the axle journal 11 does not change its vertical position.

With a view to providing a relatively large contact area immediately upon application of force by the axle journal 11 to the journal stop 24 or 25, as the case may be, each of them is provided with a film layer 40- of bearing material which has lesser wear resisting qualities than does the impact and wear resisting substrate bearing metal, such as bronze, of which the journal stops 24 and 25 are formed. Not only does the layer 40 have lesser wear resisting qualities than the substrate bearing metal of which the journal stops 24 and 25 are formed but also it can be deformed readily when subjected to the force, indicated by arrow 36, to which it is subjected on relative horizontal movement of the axle journal 11 with respect to the journal box 14. The layer 40 is deformed readily to provide a complementary cylindrical surface 41, FIG. 5, to the cylindrical surface 12 of the axle journal 11 and thus provide a load transmitting surface of substantial area such that unit pressure that is developed is not capable of rupturing and squeezing out the film 38 of lubricant that normally is carried by the cylindrical surface 12.

The layer 40 can be formed of relatively soft bearing metal, such as lead indium alloy. Also it can be formed of a fluorocarbon, such as polytetrafiuoroethylene. Examples of other materials that can be used: acetal resins, silicons, metallic soaps, and elastomers. They are characterized as having a low coefiicient of friction and adequate stability with respect to strength, heat withstandability and capability of being secured to the journal stops 24 and 25. They readily adapt themselves to various diameters of axle journal which have slightly different positions for the axis 13.

In order to apply the layer 40 to the vertical planar surfaces and 31 of the journal stops 24 and 25 methods are employed depending upon the character of the material. Where the layer is formed of relatively soft bearing metal, such as lead indium alloy, it can be applied by electro-plating or as a molten metal spray. Where a material, such as polytetrafluoroethylene or an elastomer, is employed, it can be applied by bonding, by heat and pressure, or by an adhesive.

The thickness of the layer 40 may range from 10 to 0.0762 centimeter. The thickness desired is such that only a minimum of material will be required to provide the complementary cylindrical surface 41 as shown in FIG. 5 where the contact area will be sufliciently large as to reduce the unit contact pressure and form a load transmitting surface capable of transmitting the force indicated by arrow 36 without distortion of the layer 40' beyond that required to provide the complementary cylindrical surface 41 while still retaining the back up strength of the journal stops 24 and 25 required to control motion of the axle journal 11 to protect the babbit metal liner 21 of the journal bearing 20.

What is claimed as new is:

1. In a bearing construction for a cylindrical railway car axle journal, the combination with a journal box, a wedge in said journal box, a bearing underlying said wedge and overlying said axle journal, and lubricant forming a 1111 on said axle journal, of journal stop means for limiting relative horizontal movement of said axle journal with respect to the side walls of said journal box including:

a journal stop on each side wall of said journal box having a substantially vertical planar surface facing and normally spaced from said axle journal and formed of wear resisting bearing metal, and a film layer of permanently deformable bearing material having lesser wear resisting qualities than said journal stop overlying the vertical planar substrate surface thereof and characterized by being of a thickness such that it is readily deformed immediately by pressure contact of the cylindrical surface of said axle journal to form as a result of initial contact a permanent complementary cylindrical load transmitting surface and provide initially a relatively large area of contact engagement therewith such that the unit pressure on said contact, area is insufficient to squeeze out said film of lubricant therefrom.

2. The bearing construction called for by claim 1 in which said film layer of lesser wear resisting bearing material has an initial thickness of at least 10- centimeters to control the axle journal motion in excess of the amount required to establish correct bearing relation between said axle journal and each journal stop.

3. The bearing construction called for by claim 1 in which said axle journal contacting film layer is formed of resilient material.

References Cited UNITED STATES PATENTS 2,842,409 7/1958 Christensen et al. 308-38 2,901,296 8/1959 Sweger 308-41 2,941,849 6/1960 Sale 308-40 3,115,374 2/1963 Johnson 308-40 3,132,905 5/1964 Fisher et al. 308-40 FOREIGN PATENTS 731,348 6/1955 Great Britain.

MARTIN P. SCHWADRON, Primary Examiner.

FRANK SUSKO, Examiner.

R. F. HESS, Assistant Examiner, 

